Nontypeable Haemophilus influenzae (NTHi) epidemiology

While most systemic pediatric Haemophilus influenzae infections are caused by the type b strain (Hib), nontypeable H. influenzae: (NTHi) has been considered a respiratory tract pathogen common in local infection such as acute otitis media, acute pneumonia, secondary chronic respiratory disease and other otorhinolaryngologic infections. Recent findings show, however, that NTHi also causes invasive infections such as meningitis, bacteremia, and lower respiratory tract infections such as pneumonia. A review of NTHi epidemiology from the 1990s onward shows that NTHi causes significant morbidity in pediatric acute otitis media, sinusitis, conjunctivitis and lower respiratory diseases such as pneumonia in Japan. This summary also reviews the worldwide influence of Streptococcus pneumoniae and Hib vaccines on causative pathogens, and several studies about increasing incidence of invasive infections due to NTHi. This review also touches on the emergence of treatment- and drug-resistant H. influenzae, which are now major public health challenges. As a cause of bacterial pediatric infection, NTHi is an important target for prevention.